Re: [PATCH v3] failover: fix unplug pending detection

[Gerd Hoffmann]

  Hi,

> > So, in case the first time didn't work (for example due to the guest not
> > listening because grub just doesn't do that), you can try a second time
> > once the linux kernel is up'n'running.
> > 
> > I suspect this patch will break that (didn't actually test though).
> 
> I think the solution to this problem is to not check for
> pending_deleted_event value in qmp_device_del().
> 
> But this has been explicitly added by:
> 
> commit cce8944cc9efab47d4bf29cfffb3470371c3541b
> Author: Julia Suvorova <jusual@redhat.com>
> Date:   Thu Feb 20 17:55:56 2020 +0100
> 
>     qdev-monitor: Forbid repeated device_del
> 
>     [ ... ]
> 
> So do you mean ACPI differs from PCIe Native hotplug in this case?

Yes.

It's one of the issues I'm trying to address with the

  https://gitlab.com/kraxel/qemu/-/commits/sirius/pcie-hotplug

series.  See this commit:

  
https://gitlab.com/kraxel/qemu/-/commit/675d9257d794c9d59ea7c80f48fe176a2aa3f8ba

So, yes, I think acpi and pcie hotplug should show consistent behavior
here.  And I think we need some way to recover in case the guest didn't
respond to an unplug event.  Just allowing to send device_del multiple
times looks like a sensible approach to me, and given OpenStack already
does that it looks like the most sensible way forward.

take care,
  Gerd